1. Field of the Invention
This invention relates to a system for use in sensing and managing the status of various conditions within a pocket as the pocket transports flat products from one location to another. The invention is particularly useful for sensing conditions within, and correcting certain error conditions relating to, moving pockets of a newspaper insert machine.
2. Description of the Related Art
In many machine operations, flat products such as newspapers need to be held in a certain position and transported from one area to another. One machine that is commonly employed in the newspaper and graphic arts industries is an insert machine, for use in automatically inserting flat printed inserts or other products into newspapers at high speed. The products need to be moved between machine devices such as feeders and conveyors. Examples of some prior art, commercially available insert machines are described in U.S. Pat. Nos. 4,723,770; 5,823,320; and 6,907,316, owned by the assignee of the present application. Such patents are incorporated herein by reference.
Insert machines such as those described in the above-mentioned patents typically have three basic sections that operate together in a carefully timed, coordinated fashion. First, a straight-line pocket conveyor moving on a frame is arranged to carry a series of V-shaped or U-shaped pockets along a closed path. For best operation, the pockets are typically oriented vertically or approximately vertically with the open side of the “V” facing up during the insertion process and the pockets are carried horizontally by the conveyor. An example of one type of prior art pocket is shown as element 300 in FIG. 1 of the present application. A prior art pocket of a slightly different, but related, design is shown in FIG. 3.
Each pocket is typically constructed of two flat “walls” of metal or other stiff material hinged together at the bottom. One wall, typically the leading wall, is a fixed wall that stays in a vertical orientation as the pocket moves forward, and the other wall is a moving wall that pivots back and forth relative to the fixed wall at different, timed points along the conveyor. Other devices, such as pocket grippers (see element 330 of FIG. 3) may also be attached to or carried with the pocket.
Mounted above the pocket conveyor are one or more automatic feeder devices. For example, see feeders 200 and 500 shown in FIG. I. The feeders pull sheets or other products from the bottom of a stack in a hopper and feed them down into the pockets as the pockets pass underneath.
In a typical operation, one feeder feeds a folded “jacket” of a newspaper vertically down into the pockets, one jacket per pocket, with the folded side down. Next, one edge of one side of the jacket is gripped by grippers on the pocket, and the other edge falls away or is pulled away to open the jacket. Next, as the pockets move forward, they pass under other feeders that feed inserts down into each jacket. A diagram showing a typical sequence of prior art inserting operations is shown in FIG. 2. Finally, when inserting is complete, a gripper conveyor such as structure 700 of FIG. 1 picks up the completed products from the pockets and carries them away for further handling.
Because of very high machine speeds, damaged inserts or other reasons, “problems” or error conditions can occasionally arise during the insertion process. For example, for whatever reason, a feeder may occasionally fail to feed a jacket, insert or other product into a particular pocket, may feed the product incorrectly, or a product may fall out of the pocket. Or, after feeding a jacket, which is usually a very thin and flexible newspaper product, if the jacket is not held in place within the pocket correctly, the jacket may fall closed, curl over, fold in on itself, crumple or jam within a pocket, thus preventing inserts from being properly inserted.
A need exists for a system to detect and correct for the above-mentioned error conditions. While some “repair” type systems have been installed on some prior art insert machines, such systems typically corrected for only one or a few types of problems, sometimes did not correctly fix the problem, slowed down the machine, or required manual intervention by an operator. Thus, a need exists for a system to automatically sense, monitor and manage various conditions within a pocket, and to automatically, accurately and quickly compensate for different types of error conditions that may arise.